Lapping machine



Aug. 14, 1945. R. PASH LAPPING MACHINE 4 Sheets-Sheet 1 Filed July 10,1,945

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Aug. 14, 1945. f s 2,382,903

LAPPING MACHINE Filed July 10, 1943 4 Sheets-Sheet 3 FIG. 3 GD A TTORNEY Aug. 14, 1945. sH v 2,382,903

LAPPING MACHINE Filed July 10, 1943 4 Sheets-Shet 4 I R. PAS/1' Arromvsr INVEN 709 v 'eleetrical arts.

For various uses in electrical arts it is neces-' Patented Aug. 14, 1945LAPPIN G MACHINE Robert Pash, Roselle, N. J assignor to Western ElectricCompany, Incorporated, New York, N. Y., a corporation of New YorkApplication July 10, 1943, Serial No. 494,193

2 Claims.

This invention relates to a lapping machine, and more particularly to amachine for lapping quartz crystal slices such as are used in varioussary to employ small slices of crystalline quartz having their flatfaces formed to be flat and parallel to an extreme degree of accuracy,and the slices being further formed to have to a great degree ofaccuracy, a predetermined thickness. Such slices are rough cut andformed in various ways, and are ground or "cut to approximately thedesired thickness, flatness and parallelism. The final step of lappingthese nearly finished slices down to the finished product is a trickyand diflicult task, especially on a production basis.

An object of the present invention is to provide an improved apparatusfor simultaneously lapping both sides of each of a plurality of laminarobjects ofsubstantially equal thickness, rapidly, accurately anddependably, to produce to a high degree of accuracy parallel plane facesspaced a predetermined distance apart.

With the above and other objects in view, th invention may beillustratively embodied in an apparatus for simultaneously lappingopposite faces of laminar articles and comprising a stationary annularlower lap, a centrally imperforate disk-like nest having annularlydisposed work piece receiving openings therein and restand 2|.

less thickness than the final thickness to which Other objects andfeatures of the invention will appear from the followin detaileddescription of oneembodiment thereof, taken in connection with theaccompanying drawings, in which the same reference numerals are appliedto identical parts in the several figures and in which I Fig. l is aperspective view of an apparatus constructed in accordance with theinvention;

Fig. 2 is a front elevation partly in transverse section thereof withparts in another position;

Fig. 3 is a plan view of the showing of Fig. 2 withparts broken away;

Fig. 4 is a left side elevation of the showing of Fig. 2 with partsbroken away; r

Fig. 5 is an enlarged detail view on the line 5-5 of Fig. 2;

Fig. 6 is an enlarged detail view on the line 6-6 of Fig. 3;

Fig. '7 is a detail view on the line 1-'| of Fig. 3;

Fig. 8 is a detail view on the line 8-4 of Fig. 3;

' Fig. 9 is a detached reverse plan view of the lap truing plug; and

Fig. 10 is a section on the line Hl-l0 of Fig. 9. The invention isherein disclosed as-embodied in an apparatus for simultaneously lappingboth sides of a plurality of laminar articles of approximately equalthickness.

are two cylindrlcally annular lapping blocks 20 and 2|,normallysuperimposed, as in Fig. 2, but

with the upper lap 20 arranged to be lifted and carried to one side, asin Fig'. 1. An article nest 22 is normally disposed between the two laps20 The nest 22 is a thin plate of slightly artcles are to be lapped, andmay be of any suitable material, e. g), some rust resisting metal or..alloy, hard rubber, plastic compound or the like.

In the particular apparatus disclosed, the articles '9 to be lapped aresmall square slices of crystalline quartz.

of the nest has been considerably exaggerated in the drawings.

The lower block or lap 2| rests on supports 23 formed in a basin 24supported on legs 25. In the bottom of the basin is a large centralaperture 26 with a flange 21 upturned around its rim. A spillway 28leads through the side wall of the basin at the right. The outputshaftor drive shaft 29 of a reduction gear 30, driven by a motor 3|, extendsvertically up through the aperture 26 and supports an interchangeabledriving head 32 secured on the shaft 29 by a set screw 33. The underside of the head has a pendent skirt 34 extending downward outside andbelow the top of the flange 21. A verticaljthreaded drive pin 35 ismounted in a correspondingly threaded vertical bore 36 in the top of thehead 32 and offset laterally from the axis of rotation of the head. Thepin 35 is held at an'adjustable height in the bore 36 by means of a jamnut 31. Other bores, such as I36, may be formed in the head at otheroffset distances from the axis of the head and may be closed when not inuse by screws I35.

The top end of the pin 35 enters a funnelshaped recess 38 ending in acorrespondingly formed bottom in an eyelet member 39 secured to thecenter of the under side of the nest 22. he

pin 35 fitsv neatly but not snugly into the recess 38, being free toturn therein but without appreciable freedom to move therein otherwise.

Fundamental elements For clarity of understanding, the j thickness ofthese slices relative to the thickness shown in Fig. 6. The screws 4|enter corresponding conical recesses 44 in the cylindrical side wall ofthe lap 20 atopposite ends of a diameter thereshaft 59.

of. Preferably the lap is provided with several pair of such recesseaasshown. The lap 2| is also provided with identically similar recesses I44for a reason to be explained hereinafter.

The ring 40 is'secured to one end of a supported rod 45 extendingoutwardly from the ring, in the plane thereof, and at right angles to aline through the screws 4|, 4|. The other end of the rod is journalled,to be freely rotatable about its axis, in a bearing 46 and held againstlongitudinal motion therein by collars 41, 41 and set screws 48, 59, asbest shown in Fig. 7. Thus the lap 20 is tiltable about the axis of thescrews 4| and also about the axis of the rod 45 to follow irregularitiesin the combined surface of the crystal slices l9. The bearing 46 ispivotally supported in a yoke 49, so that the rod 45 is also pivotablevertically about a horizontal axis at right angles to its own axis. Theyoke 49 is mounted in the machine frame to be pivotable about a verticalaxis, to allow the lap 2|! to be swung into either of the positionsshown' respectively in Figs. 1 and 3. The position of Fig. 1 may betermed the loading position, and that of Fig. 3 the lapping or operatingposition. As the rod 45 swings between these two extreme positions, itmoves within and is limited by a rectangulan frame consisting of abottom crossbar 50 rigidly secured on the machine frame, an uprightouter post 5| secured on the bar 50, an upright inner post 52 mounted onthe machine frame, and a top crossbar 53 mounted on the't'wo posts.

When the lap 20 is in the lapping position (Fig. 3) and it is desired tomove itto the loading posiition (Fig 1) to inspect the work or tore-load the nest or for any other reason, it is generally preferable toslide the lap 20 laterally away without lifting it from the work, lestpieces of work adhere to the lap 20 and be lifted out of the nest andthus displaced or even carried away, but when this lap is returned tothe lapping position it is generally preferable to lift it across to aposition over the nest and lower it into place, lest pieces of work beknocked out of the nest. Hence the frame just described is made highenough inside to permit of these movements. For convenience the taperedretaining member 54 with a flange 55 behind which the rod 45 isremovably held against accidental displacement inthe loading position,is mounted on the outer portion'of the bar 50.

A stop member 58 is mounted on the post 52 by means of screws 51entering corresponding bores in the post and passing through oversizeholes in the member 56 so thatthis latter is shiftably adjustable on thepost. The rod 45 when swung into operating position, stops against themember 56; and this is made adjustable as described in order to locatethe lap 2|! accurately over the lap 2|. To retain the lap 20 in thisposition, a latch 58 is rigidly mounted on a' shaft 59 joumalled in thepost 52 and also in a bearing 54 mounted on the machine frame. Thebearing 50- is held in place by screws 6| passing through oversize holesin a bearing body and into themachine frame. Thus the bearing 50 may beadiusted to move the shaft 59 longitudinally of itself to allow :Iustspace enough between the latch 60 and the stop 56 for the rod 45 to fitbetween when the lap 20 is accurately in operating position. The latchmay be turned into its operative position, best shown in Fig. 8, or backout of the way, as in Fig. 1, by means of a handle 62 on the A countingdevice 63 actuated by a solenoid 64 may be mounted conveniently on themachine frame and actuatedby a micro-switch 65 mounted conveniently onthe casing of the reduction gear 30 adjacent to the shaft 29. The skirt34 of the driving head 32 may then have a downwardly projecting finger66 to actuate .the lever 61 of the micro-switch 65 once at eachrevolution of the head.

The two laps 20 and 2| are identically alike in size and shape. Thecentral apertures 68 and 89 respectively are of the same diameter anddepth. Each has a plane lapping face, l0 and 1! respectively, in whichare formed concentric grooves 72 to aid in distributing the mixture ofabrasive dust and water or other vehicle use for the lapping. This maybe easily supplied, even when the machine is in operation, to the broadshallow channel I3 formed in the top surface of the lap 20 from whichvertical bores I4 lead down through the body of the lap and through itslower surface it. Since the nest 22 moves eccentrically as hereinafterdescribed, the abrasive is also delivered through these bores to theface H of the lap 2|. Excess abrasive material washes down over theouter and inner faces of the lap 2| into the basin 24 and is dischargedinto any convenientreceptacle (not shown), through thespillway 28. Theskirt 34 on the head 32 and the flange 27 on the bowl 24 prevent accessof the abrasive to the driving unit and its bearings below the haft;29.v

With the machine in the position shown in Fig. 1, finished work pieces|9 may be removed. Preferably, through not necessarily, theempty nest isremoved and a fresh starting supply of nest 22. Were the nest coaxialwith the two laps,

the apertures -15 and the work blanks in them would lie with theircenters on a circle midway between the inner and outer edges of theworking face H of the lap 2|, and hence also in like relation to theface 10 of the lap 20 when-the latter is in lapping position (Fi 2).Since the center of the nest is held off center by the pin 35, this ringof work pieces is always eccentric to the two laps, 'as shown, when themachine is operating.

The nest having been put in place and filled with blanks, abrasive issmeared over the nest and blanks, and the top lap 20. is lifted overfrom the position of Fig. 1 and placed over the work in the position ofFig. 3. Abrasive is supplied to friction of the laps on the right sidehalf circle of blanks than on the left half circle. Hence under the urgeof the driving pin, which is freely in Figs. 9 and 10. The nest 22 isremoved from the machine, and the plug 1', dimensioned to fit into thebore 68 of the lap 20, is placed in the bore. The body of the plug iscut away as shown in the reverse plan shown in Fig. 9, so that only thearcuately corresponding short faces I1 and II bear against the wall ofthe bore '8 and are held there by the set screw 19. The flange 8| restson top of the lap. The stem 8! extends down into the normal position ofthe nest eyelet I8 and is formed with a funnelled aperture 82 formedlike the aperture 38 of the eyelet to receive the top of the driving pin35. Thus the lap 20 may be driven in "eccentric revolution on the lap2|. By working together in this fashion the two laps II and 2| and athird lap identically like either 20 or 2|, in all possible combinationsof pairs of the three laps, the working faces of the three are madeplane. i

It will be noted that in the apparatus described, when the upper lap 20is swung aside as in Fig. 1, there is no apparatus part overhanging theheld of operation. The entire nest 22 and all of its contents of workpieces is are uncb structedly open to view, to. manipulation and toinspection, because the operating drive of'the apparatus is from belowthe laps. Because the nest has no central perforation, being driven bymeans of the eyelet 39 instead of a central perforation, there is nodrip of abrasive andwater down upon the driving means from the nest.Excess abrasive and water run down the inner face of the stationary lap2| and drop into the bowl; but do not run down over any moving part tobe thrown around, except possibly to some small extent between the nestapertures and the work pieces I! therein. However, any drip from thisruns down the skirt 34 of the head 32 into the bowl. Thus the drivingmechanism is wholly protected against. access of abrasive thereto eventhough.

it is located directly under the center of the field of lapping action.

The lap 2| is held solidly stationary by the shoulder ll on the supports23. The lap 20, when in lapping position, is held immovably in positionby the latch 58 and stop member 56 acting on the support rod 45.Nevertheless, the lapis free to follow irregularities in the gross,combined surface of the workpieces l9, as these are rotated by the nest22 between the laps, by virtue of the gimbal mounting of the lap 20 inthe pivot screws 4|, 4|, and in the bearing 46. l

The embodiment disclosed and described above is illustrative and may bevariously modified and departed from without departing from the spiritand scope of the invention as particularly described and pointed out inthe appended claims.

What is claimed is:

period of service, use is made of the device shown 1. Apparatus forsimultaneously lapping opposite faces of laminar articles and comprisinga stationary annular horizontally disposed lower lap, a disk-like nesthaving annularly disposed workpiece receiving openings therein andresting on the lower lap, an annular upper lap to rest on workpieces inthe openings of the nest and resting on the lower lap, the two lapsbeing normally substantially coaxial, means to drivethe nest in circularmotion eccentric to the laps, gimbal mountings to normally hold theupper lap coaxial to the lower lap with freedom to tilt as necessary tofollow irregularities of thegross upper surface of the workpieces and toprevent any rotary motion of the upper lap about its axis, andsupporting means secured to the gimbal mountings and movable to swingthe mountings and therewith the upper lap to slide the upper laphorizontally from the workpieces into a position wholly apart from thenest and lower lap leaving the workpieces accessibly uncovered, and

to swing the upper lap back into position above the lower lap and thendownwardly upon-workpieces thereon, the said gimbal mountings andsupporting means comprising a yoke whose arms are pivotably attached tothe upper lap to permit the same to rock therein in the plane of thestem of the yoke, a rotatable vertical shaft, and a substantiallyhorizontal sleeve to receive and support the stem of the yoke thereinwith freedom for the yoke and the lap held in the yoke to rocktransversely to the stem of the yoke, the sleeve being mounted on theshaft to be rotatable therewith.

2. A'pparatus-for simultaneously lapping opposite faces of laminararticles and comprising a stationary annular horizontally disposed lowerlap, a disk-like nest having annularly disposed workpiece receivingopenings therein and resting so on the lower lap, an annular upper lapto rest on workpieces in the openings of the nest and resting on thelower lap, the two laps being normally substantially coaxial, means todrive the nest in circular motion eccentric to the laps, simbalmountings to normally hold the upper lap coaxial to the lower lap withfreedom to tilt as necessary to follow irregularities of the gross uppersurface of the workpieces to prevent any rotary motion of the upper lapabout its axis, and supporting means secured to the gimbal mountings andmovable to swing the mountings and therewith the upper lap to slide theupper lap horizontally from the workpieces into a position wholly apartfrom the nest and lower lap leaving the workpieces accessibly uncovered,and to swing the upper lap back intoposition above the lower lap andthen downwardly upon workpieces thereon, the said gimbal mountings andsupporting means comprising a yoke whose arms are pivotably attached tothe'upper lap to permit the same to rock therein in the plane of thestem of the yoke, a rotatable vertical shaft, and a substantiallyhorizontal port the stem of the yoke therein with freedom for the yokeand the lap held in the yoke to rock transversely to the stem of theyoke, the sleeve being mounted on the shaft to be rotatable with,together with a latch to releasably hold the yoke in position when theupper lap is in operative position coaxial with the lower lap.

- ROBERT PABH.

sleeve to receive and supthere-

